Self adjusting disc brake assembly

ABSTRACT

The invention relates to a self-adjusting brake assembly for retarding the rotational movement of a shaft or axle having a plurality of rotary disc members mounted for both rotational movement therewith and axial movement relative thereto. The assembly includes a plurality of fixed discs carried by a stationary housing, and an actuator plate hydraulically movable so as to force the disc members into frictional engagement with the fixed discs in order to stop the shaft or axle. The assembly is provided with automatic adjuster means for maintaining constant the distance required for moving the actuator plate into engagement with the disc members and discs.

United States Patent Kershner 154] SELF-ADJUSTING DISC BRAKE ASSEMBLY[75] Inventor: Osborn A. Kershner, St. Joseph,

Mich.

[73] Assignee: Lambert Brake Corporation, St.

Joseph, Mich.

[22] Filed: Sept. 10, 1970 [21] App]. No.: 71,022

[52] U.S. Cl. ..188/196 P, 188/71.8 [51] Int. Cl ..Fl6d 65/54 [58] Fieldof Search ..188/7l.7,71.8,196P

[56] References Cited UNITED STATES PATENTS 2,384,297 9/1945 Goepfrich..l88/7l.8 2,536,269 1/1951 Driscoll ..l88/7l.8

2,888,109 5/1959 Tankersley ..188/7l.8 X 3,068,965 12/1962 Mossey..188/196 P X 9/1960 Smellie ..188/196 P X 8/1967 Guilhnmat ..188/196 P[57] ABSTRACT The invention relates to a self-adjusting brake assemblyfor retarding the rotational movement of a shaft or axle having aplurality of rotary disc members mounted for both rotational movementtherewith and axial movement relative thereto. The assembly includes aplurality of fixed discs carried by a stationary housing, and anactuator plate hydraulically movable so as to force the disc membersinto frictional engagement with the fixed discs in order to stop theshaft or axle. The assembly is provided with automatic adjuster meansfor maintaining constant the distance required for moving the actuatorplate into engagement with the disc members and discs.

7 Claims, 7 Drawing Figures PATENTEUMARNIQB 722,637

SHEET 3 OF 3 WZZ/l jvemr Qibor A -Za W WM zdwg SELF-ADJUSTING DISC BRAKEASSEMBLY SUMMARY OF THE INVENTION The present invention relatesgenerally to a disc brake assembly and more particularly to a disc brakeassembly employing self-adjusting means for compensating for disc wear.

DISTINCTION OVER THE PRIOR ART AND OBJECTS Disc brakes of the generaltype disclosed and claimed herein are generally used for retarding themovement of a rotating shaft or axle and are quite well known. This typeof brake usually includes a plurality of braking discs, which aremounted to the shaft for both rotational movement therewith and axialmovement relative thereto. A movable actuator plate is provided forengaging and shifting the braking discs against corresponding fixedsurfaces which due to the friction therebetween causes the discs andtherefore the shaft to cease from rotating.

It is apparent that as the braking discs function in the aforementionedmanner, they tend to wear thin. This, of course, increases the runningclearance between the discs, which, in turn, requires a greater shiftingdistance of the movable actuator plate for stopping the shaft.Therefore, the time required for stopping the shaft is increased, whichthereby decreases the efficiency of the brakes and requires more brakefluid per application.

In the past, the aforementioned problem has been dealt with by providinga method of automatically shifting the actuator plate in response to theamount of wear on the discs. One such method disclosed by the prior artcontemplates the use of an elongated threaded screw thread mountedthrough the actuatorplate and having a force applied to one end thereoffor longitudinally rotating the screw through the actuator plate forthereby repositioning the latter with respect to the braking discs.While this method is quite satisfactory from a functional standpoint, itlacks certain simplicity which is required for manufacturing theover-all brake assembly in a more economical manner.

Accordingly, a general object of the present invention is to provide anew and'improved self-adjusting brake assembly which is both simple indesign and economical to manufacture.

A'more particular object of the present invention is to provide a discbrake assembly employing a new and improved means for compensating forbrake lining wear, which means is both simple in design and economicalto manufacture.

These and other objects and features of the invention will become moreapparent from a reading of the following descriptions.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view of aself-adjusting disc brake assembly constructed in accordance with thepresent invention, this view being taken generally along the line ll inFIG. 2;

FIG. 2 is a sectional view taken generally along the line 22 in FIG. 1;

FIG. 3 is an enlarged sectional view taken generally along the line 3-3in FIG. 1, specifically showing the self-adjustin g means used with thebrake assembly;

FIG. 4 is an enlarged sectional view taken generally along the line 4-4in FIG. I specifically showing the self-adjusting means of FIG. 3;

FIG. 5 is an enlarged side sectional view taken generally along line 3-3in FIG. 1, specifically displaying the brake assembly in its initialenergized position;

FIG. 6 is a similar view to that of FIG. 5 specifically showingthebraking assembly in its initial' energized position after substantialuse; and

FIG. 7 is a similar view to that of FIGS. 5 and 6 however with the brakeassembly being shown in its deenergized position after substantial use.

DETAILED DESCRIPTION Turning now to the drawings wherein like componentsare designated by like reference numerals throughout the variousfigures, a self-adjusting brake assembly, constructed in accordance withthe present invention, is illustrated in FIGS. 1 and 2 and designated bythe reference numeral 10. The assembly is provided for retarding orstopping the rotational movement of a cylindrical elongated shaft oraxle 12. In order to accomplish this, the shaft or axle includes aplurality of circumferentially spaced and longitudinally extendingsplines or channels 14 which receive a plurality of circumscribing,longitudinally spaced and substantially flat annular rotary disc members16, 18 and 20, which are preferably constructed of stamped sheet metal.In this manner, disc members 16, 18 and 20 not only rotate along withshaft 12, but also are capable of axially or longitudinally shiftingrelative thereto, which, as will be seen hereinafter, is necessary forstopping the rotational movement of the shaft. While only three discmembers are shown, it is to be understood that any reasonable number iscontemplated by the invention.

Directing attention to FIG. 2, brake assembly 10 is shown to include a'substantially cylindrical closed housing 22 which is partially opened atits right end 24, as viewed in FIG. 2, for receiving one end portion ofshaft or axle 12, the housing being fixed thereat by a plurality ofcircumferentially spaced apertured lugs 25 formed therewith. An annularbearing 26 mounted within the housing and circumscribing shaft 12reduces frictional drag and therefore allows the shaft to rotate freelyrelative to the housing. Also mounted within housing 22 are twoelongated cylindrical torque pins 28 which are diametrically spaced fromeach other on opposite sides of shaft 12, as viewed in, FIG. 1. Thetorque pins, which are in parallel relationship with shaft 12, extendbetween and are rigidly held at opposite ends to the right end 24 ofhousing 22 and a left end 30 thereof, as viewed in FIG. 2, and areprovided for reasons discussed below.

Brake assembly 10 further includes two substantially flat annular fixeddisc members 32 and 34 which are positionedbetween rotating disc members16, 18 and- 20, and which circumscribe rotating shaft 12, as illustratedin FIG. 2. The fixed discs'32 and 34 are held within housing 22 merelyby respective pairs of U- shaped extension flanges 36 and 38 whichextend radially outwardly from diametrically opposite peripheral edgeportions of the fixed disc members, as illustrated in FIG. 2. The legsof each of these ufshaped extension flanges are positioned for receivinga corresponding torque pin 28 therebetween, for preventing rotationalmovement of the fixed disc members 32 and 34. However, it should benoted that the fixed disc members are free to shift longitudinally oraxially relative to the shaft, so that opposite substantially flatannular side surfaces 40 and 42 of the respective fixed disc membersengage adjacent corresponding sides of rotary disc members 16, 18 and 20in a manner and for reasons to be described below. In this regard, eachof the annular rotary disc members includes a pair of annular frictionpads 44, 46 and 48 which are positioned on opposite sides of therespective rotary member for frictionally engaging with the fixed discs.7

An annular actuator plate 50 is also disposed around shaft or axle 12within housing 22 and positioned in confronting relationship with andbetween the annular rotary disc member 16 and the left end 30 of housingof rotary disc members, 18 and 20, and therefore shaft or axle 12. Asnoted in FIG. 2, annular bearing seals 72 and 74 are disposed aroundpiston 68 so as to prevent the fluid from either leaving the housingthrough end 30 or from entering the housing through tend to wear thin soas to progressively increase the 22, as illustrated in FIG. 27 Likefixed disc members 32 l and 34, the actuator plate includesdiametrically spaced U-shaped extension flanges 52 extending fromopposite peripheral edge portions for receiving torque pins 28, asillustrated best in FIG. 1. In this manner, actuator plate 50 is freelyshiftable in an axial or longitudinal direction relative to shaft 12while being incapable of rotational movement about the longitudinal axisof the shaft. I

The actuator plate is spring-biased against the flat verticallyextending annular inner abutment surface 54 formed with the left end 30of housing 22 by a plurality of elongated spring elements 56. As seen inFIG. 4, each of these spring elements is mounted within a cavity 58provided by an inwardly extending vertical abutment surface 60 ofhousing 22, the surface 60 being laterally spaced from andin confrontingrelationship with the surface 54, as illustrated in FIG. 2. The springelement thereafter extends outwardly from surface .60 and against theinner surface of a corresponding extension flange 62 formed with andextending outwardly from a peripheral'edge portion of actuator plate 50.As noted in FIG. 1, there are two such peripheral extension flanges 62and four spring elements 56 which provide sufficient force foradequately biasing the actuator plate against surfaces 54 of housing 22.

In order to stop the rotational movement of shaft or axle 12, it isreadily apparent that actuator plate 50 must be driven to the right, asviewed in FIG.2, or axially away from surface 54 of housing 22, so as torunning clearance '75 required when the brake assembly is in adeenergized state. Accordingly, if left unadjusted, the actuator plate50 would have to be shifted continuously greater distances so as tocompensate for this increase in running clearance, which in turn wouldnecessarily cause an increase in braking time and use of excessive brakefluid.

In accordance with the present invention, the brake assembly is providedwith automatic adjuster means for maintaining substantially v constantthe distance required for axially or longitudinally shifting theactuator plate 50 in order to stop the rotating disc members andtherefore the shaft 12, regardless of the amount of wear to the frictionpads. Such automatic adjuster means are preferably provided atdiametrically opposite sides of the actuator plate 50, as illustrated inFIG. 1, and are generally designated by the reference numeral 76. Whileonly one such means is necessary, two or more thereof provides for amore reliable operation. Referring more particularly to FIGS. 3 through7, one such automatic adjuster 76 is clearly shown in detail, and it isto be understood that the other adjuster (or others which may beprovided) with which the brake is preferably provided will correspondthereto.

The automatic adjusters each include a cylindrical elongated pin element78 having a substantially smooth longitudinal surface and mounted forlongitudinally slidable movement through an opening 80 extending throughthe extension flange 62 of adjuster plate 50, as

squeeze or otherwise force the rotary disc members 16,

l8 and 20 into frictional engagement with fixed disc members 32 and 34,all of which are frictionally squeezed against the inner surface 64 ofactuator plate and the vertically extending annular inner surface 66defined by the right end 24 of housing 22. In this manner, therotational movement of rotating disc members l6, l8 and 20 is retarded,which in turn retards or stops the rotational movement of shaft 12.

In order to shift actuator plate 50 in the aforementioned manner, ahydraulically operated piston 68 is positioned within housing 22 betweenactuator plate 50 and left end 30 and is mounted thereat for movementperpendicularly towards and away from the actuator plate. A hydraulicinlet 70 is provided in the left end 30 of housing 22, as illustrated inFIG. 2, for directing fluid, from a source not shown, to the piston,whereupon the piston moves into engagement with the actuator plate forshifting the latter in the aforementioned manner and thereby stoppingthe rotational movement illustrated in FIG. 2. The pin'element extendsoutwardly from opposite sides of the actuator plate and perpendiculartherewith, so that the right transverse edge 82 of the pin. element isin confronting parallel relationship with'the surface 60 of housing 22,as seen in FIG. 2, while the left transverse edge 84 is in confrontingparallel relationship with the inner vertical surface 86 provided by theopening or channel 88 extending inwardly from the surface 54 of thehousing.

Turning to FIG. 3, opening is partially defined by a bore 81 extendingthrough extension flange 62 and providing a cylindrical substantiallysmooth bearing surface 83 which aids in slidably, guiding pin element 78' axial distance of bearing surface 83 so that the latter is relativelyshort as compared to the over-all thickness of actuator plate 50. Inthis manner, frictional drag between the bearing surface and pin element78 is minimized, so that the bearing surface acts more accurately as aguide for the pin element.

Each of the automatic adjusters includes a one-way washer assembly 90which limits the axial slidable movement of pin element 78 to thedirection indicated by arrow 92 or longitudinally to the left as viewedin FIG. 3, and prevents the pin from moving longitudinally or axially tothe right as viewed in that figure. This is achieved by the utilizationof a pair of annular members 94 and 96 (or any reasonable numberincluding one thereof) which are concentrically disposed around pinelement 78, and which are maintained in spaced-apart relationship withrespect to each other by an annular spacer washer 98. The annularmembers 94 and 96 are positioned within the counter-bore 87 of extensionflange 62 and spring forced against the inwardly extending annularshoulder 100 by a spring washer 99 which, in turn, is locked in place bya snap ring 101 held within an annular groove 103 circumscribingcounter-bore 87.

The inner peripheral edge of each of the annular members 94 and 96includes inwardly extending circumferentially spaced resilient teeth 102and 104, respectively, which extend axially at an angle, slightly to theleft as viewed in FIG. 3, and into counter-bore 85 just below shoulder100. In this manner, counter-bore 85 provides clearance for the teethrelative to bearing surface 83.

The inner edges of teeth 102 and 104 display circles having diameterssubstantially less than the cross-sectional diameter of pin element 78so that the engaging edges thereof aggressively engage the surface ofthe pin element for preventing the latter from moving in a directionagainst the arrow 92. It is readily apparent, however, that due to theangle of teeth 102 and 104, the pin element may readily slide in thedirection of arrow 92. It should be noted, that the annular members 102and 104 are constructed of material substantially harder than that ofpin element 78, so that the inner tooth edges score or otherwise cutinto the pin element for more reliably preventing the latter from movingagainst arrow 92.

Because pin element 78 relies solely on assembly 90 (as opposed to bore81) for its one-way operating limitation, the bore, along withcounter-bores 85 and 87, may be of greater tolerances, which in turnminimizes the cost of manufacture.

Turning now to the manner in which the automatic adjuster meansoperates, attention is directed back to FIGv 2 which shows the brakeassembly in a deenergized position. In this position, actuator plate 50is held in its biased position against surface 54 of housing 22, whilethe left transverse edge 84 of pin element 78 engages surface 86. Inthis manner, running clearance 75 exists on each side of each annularrotating disc member 16, 18 and 20, respectively, so that the latter mayfreely rotate and thereby allow shaft or axle 12 to so rotate.

Turning to FIG. 5, the brake assembly 10 is shown in its initialenergizing or braking condition, that is, with actuator plate 50 shiftedlongitudinally to the right, for frictionally stopping the rotationalmovement of the rotating discs 16, 18 and 20. In this state, it canreadily be seen that the actuator plate is shifted a distance L awayfrom the housing surface 54, causing the left transverse edge of pinelement 78 to move a like distance away from housing surface 86. Itshould be noted, that with the aforementioned movement of actuator plate50 and pin element 78, the right transverse edge 82 of pin element 78just barely engages the surface of housing22. Upon deenergizing thebrake assembly, the actuator plate 50 and pin element 78, of course,return to their biased positions, through the force of spring elements56, in the manner described above.

As stated above, as the friction pads 44, 46 and 48 continuouslyfunction to stop the rotational movement of shaft 12, they progressivelywear thin, which in turn causes great running clearances, so that theactuator plate 50 is required to move a greater distance during brakeenergization. This is illustrated in FIG. 6, where the brake assembly isshown in its energized position after being in use for a period of time.As noted there, actuator plate 50 is now positioned a distance L+AL fromhousing surface 54, the additional incremental distance AL representingthe combined wear of friction .pads 44, 46 and 48 or combined increasein running clearance. As the actuator plate moves through this distanceL+AL, the housing surface 60 engages the right transverse edge 82 of pinelement 78 and shifts the latter a distance AL, relative to the actuatorplate, and annular members 94 and 96 in the direction indicated by arrow106. Upon deenergizing the brake assembly and returning the actuatorplate to its biased position, as illustrated in FIG. 7, the lefttransverse edge 84 of pin element 78, which has been shifted to the lefta distance AL relative to the actuator plate, engages the housingsurface 86 for thereby repositioning the act ator plate a distance ALfrom the housing surface 54. In this manner, when the brake assembly 10is again energized, the actuator plate 50 is required to move only adistance L for stopping the rotational movement of shaft or axle l2.

While the operation of automatic adjuster means 76 has been described inrather spaced-apart steps, it is obvious that as the friction pads 44,46 and 48 progressively wear, the pin elements 76 progressively shift tothe left, as viewed in FIGS. 5 through 7, so that the distance requiredto move actuator plate 50 remains substantially constant, i.e., adistance L. This, of course, provides for a substantially constantbraking time and therefore a more accurate and reliable assembly.

While a preferred embodiment of the invention has been shown, it shouldbe understood, of course, that the invention is not limited thereto,since many modifications may be made. It is, therefore, contemplated tocover by the present application any such modifications as fall withinthe true spirit and scope of the appended claims.

The invention is claimed as follows:

1. In a disc brake assembly, an actuator disc axially shiftable betweena first retracted position and a second advanced brake energizingposition, said disc including a bore having a portion that constitutes aslide bearing and guide means having an axis parallel to a central axisof the disc, said bore also including adjacent counterbore portions ofdifferent diameters defining a shoulder in the larger diametercounterbore portion, said slide bearing and guide means having an axialdimension that is small as compared to the axial dimension of said discat said bore, an elongated pin of predetermined diameter and lengthaxially slidably disposed in said bearing and guide means projectingaxially through said counterbore portions and from opposite sides of thedisc for engagement with first and second fixed abutment surfaces of thebrake assembly spaced apart a distance slightly greater than saidpredetermined length and substantially in accordance with apredetermined running clearance for the brake assembly, and means fixedto and carried by said actuating disc and engaging said pin forpositively limiting slidable movement of the pin in one direction whilepermitting movement in an opposition direction relative to the actuatordisc for compensating for wear in the brake assembly and maintaining thedesired running clearance, said last-named means being substantiallyentirely within the larger of said counterbore portions and being seatedagainst said shoulder.

2. A disc brake assembly according to claim 1 wherein said last-namedmeans includes a plurality of annular locking members with a pluralityof annularly arranged resilient axially inclined teeth presenting toothedges aggressively engaging said pin.

3. A disc brake assembly according to claim 2 wherein said tooth edgesnormally define a circle having a diameter substantially less than thediameter of said pin for causing said tooth edges to cut away thesurface portion of said pin upon movement of the pin relative to thedisc in said opposite direction.

4. A disc brake assembly according to claim 1 wherein said bearing andguide means has a diameter larger than the diameter of said pin forpermitting the pin to slide freely therethrough and said locking meansare axially spaced from said bearing means for preventing interferencebetween said teeth and said bearing means.

5. A disc brake assembly according to claim 1, wherein thelast-mentioned means includes an annular locking member with a pluralityof annularly arranged resilient axially inclined teeth presenting toothedges within the smaller diameter counterbore portion aggressivelyengaging said pin.

6. A disc brake assembly according to claim 1, wherein the last-namedmeans includes a plurality of annular locking members separated byspacer washer means and the locking members having annularly arrangedresilient axially inclined teeth presenting tooth edges aggressivelyengaging said pin.

7. A disc brake assembly according to claim 6, wherein the teeth of theannular locking member adjacent said shoulder extend within the smallerdiameter counterbore portion.

1. In a disc brake assembly, an actuator disc axially shiftable betweena first retracted position and a second advanced brake energizingposition, said disc including a bore having a portion that constitutes aslide bearing and guide means having an axis parallel to a central axisof the disc, said bore also including adjacent counterbore portions ofdifferent diameters defining a shoulder in the larger diametercounterbore portion, said slide bearing and guide means having an axialdimension that is small as compared to the axial dimension of said discat said bore, an elongated pin of predetermined diameter and lengthaxially slidably disposed in said bearing and guide means projectingaxially through said counterbore portions and from opposite sides of thedisc for engagement with first and second fixed abutment surfaces of thebrake assembly spaced apart a distance slightly greater than saidpredetermined length and substantially in accordance with apredetermined running clearance for the brake assembly, and means fixedto and carried by said actuating disc and engaging said pin forpositively limiting slidable movement of the pin in one direction whilepermitting movement in an opposition direction relative to the actuatordisc for compensating for wear in the brake assembly and maintaining thedesired running clearance, said last-named means being substantiallyentirely within the larger of said counterbore portions and being seatedagainst said shoulder.
 2. A disc brake assembly according to claim 1wherein said last-named means includes a plurality of annular lockingmembers with a plurality of annularly arranged resilient axiallyinclined teeth presenting tooth edges aggressively engaging said pin. 3.A disc brake assembly according to claim 2 wherein said tooth edgesnormally define a circle having a diameter substantially less than thediameter of said pin for causing said tooth edges to cut away thesurface portion of said pin upon movement of the pin relative to thedisc in said opposite direction.
 4. A disc brake assembly according toclaim 1 wherein said bearing and guide means has a diameter larger thanthe diameter of said pin for permitting the pin to slide freelytherethrough and said locking means are axially spaced from said bearingmeans for preventing interference between said teeth and said bearingmeans.
 5. A disc brake assembly according to claim 1, wherein thelast-mentioned means includes an annular locking member with a pluralityof annularly arranged resilient axially inclined teeth presenting toothedges within the smaller diameter counterbore portion aggressivelyengaging said pin.
 6. A disc brake assembly according to claim 1,wherein the last-named means includes a plurality of annular lockingmembers separated by spacer washer means and the locking members havingannularly arranged resilient axially inclined teeth presenting toothedges aggressively engaging said pin.
 7. A disc brake assembly accordingto claim 6, wherein the teeth of the annular locking member adjacentsaid shouLder extend within the smaller diameter counterbore portion.